Various methods have been employed to produce a visual image by heat treatment. For instance, as described in "Modern Hard Copy Printer Technology", Imaging, Part 2, special edition of Photographic Industry (Shashin Kogyo Shuppan Sha, Jul. 20, 1988), pp 63-113, an image can be produced and transferred to recording paper by the so-called thermal transfer method in which a sheet of recording paper is laid on top of a thermal transfer ribbon having a support and provided thereon a layer comprising a binder with a dye or a pigment dispersed therein, and thermal energy corresponding to image information is supplied by a thermal head from the backside of the thermal transfer ribbon, thereby allowing an image to be transferred and recorded on the recording paper.
Also known is the heat-processing method in which an image, either monochromatic or colored, is formed by exposing a silver halide light-sensitive material to light, followed by heat-processing. Details of this method are described in the summary of the 17th symposium of Japan Photographic Society, "A study of heat-processable silver salt recording system", May 1987. In the heat processing method, a silver or dye image is produced by subjecting a heat-processable light-sensitive material comprising a light-sensitive silver halide, a binder and a reductant to imagewise exposure to light, followed by heating and pressing. A dye image formed by this process is transferred to an image-receiving element, the image-receiving element is removed from the light-sensitive material, forming a vivid dye-image.
The above thermal image transfer method and the heat-processing method have an advantage over conventional wet processing as they require no liquid processing, but have such a defect that adhesion between a support and an image-receiving layer tends to lower during image-forming performed at a high temperature.
Baryta paper, art paper, polyethylene-coated paper, plastic films and others have been employed as the support for an image-receiving element. These conventional supports, however, exhibit poor adhesion to an image-receiving layer.
Meanwhile, plastic films, due to their improved surface luster, surface smoothness and transparency, have come to be employed more widely than ever as the support, since they are suited to image appreciation using a transmitted light, such as image appreciation by OHP, and can satisfy a recent demand for a high image quality. Of such plastic films, films of polyester resins, in particular, polyethylene terephthalate, have been employed most widely. However, an image-receiving element prepared by providing an image-receiving layer directly on a polyethylene terepthalate film encounters such a problem that the image-receiving layer tends to peel off from the support during heat treatment for the formation and transfer of an image. The removal of an image-receiving layer from a support may result in ununiform developing. In addition, in such image-receiving element, removal of an image-receiving layer from a support may occur even after an image is transferred thereonto, which significantly impairs the commercial value of the image-receiving element.